diff --git a/src/errno.asm b/src/errno.asm
index 5d06c89..038adc0 100755
--- a/src/errno.asm
+++ b/src/errno.asm
@@ -20,6 +20,7 @@ pub const SCREEN_INVALID_MODE  = 0x0001
 pub const SCREEN_INVALID_WIDTH = 0x0003
 pub const SCREEN_FB_TOO_SMALL  = 0x0005
 pub const SCREEN_OUTSIDE_FB    = 0x0007
+pub const BUFFER_DEPTH_MISMATCH= 0x0009
 
 pub const MAGIC_BAD            = 0x8001